dracut: include all USB controllers drivers

dracut in Fedora 20 doesn't know about *-pci modules (which were split
of *-hcd). So add them manually, in all flavors (ehci, ohci, xhci).

Fixes QubesOS/qubes-issues#1517

dracut/modules.d/90extra-modules/module-setup.sh

@@ -3,5 +3,9 @@
 
 installkernel() {
     # ehci-hcd split off
-    instmods ehci-pci ehci-platform || :
+    hostonly='' instmods ehci-pci ehci-platform || :
+    # xhci-hcd split off
+    hostonly='' instmods xhci-pci xhci-plat-hcd || :
+    # ohci-hcd split off
+    hostonly='' instmods ohci-pci || :
 }